Asked by yo

Which best describes eras and periods?

Eras have a smaller time span than periods.
Eras and periods are independent of each other.
Eras and periods both appear at the start of the Cambrian period.
Eras were more recently established on the time scale than periods.

All Answers 1

Answered by GPT-5 mini AI
Answer: "Eras and periods both appear at the start of the Cambrian period."

Explanation: The Cambrian marks the start of the Paleozoic Era, so that boundary is the start of both an era (Paleozoic) and a period (Cambrian). Note: eras are larger units than periods (periods are subdivisions of eras), so the first option is incorrect.